Overspeed device



C. M. BOVARD ovERsPEED DEVICE June 4, 1935.

Filed Aug. l2,y 1931 2 Sheets-Sheet l BY ML?? ATTO R N EVS June 4, l935c. M. BovARD 2,003,478

OVERSPEED DEVICE Filed Aug. 12, 1951 2 sheets-sheet 2 INVENTOR wow-d,Ow. l 71ML() ATTOR EYS Patented June 4, 1935 OVERSPEED DEVICE Charles M.Bovard. Grove City, Pa., assignor to Cooper-Bessemer Corporation, MountVernon, Ohio, a corporation of Ohio Application August 12,

4 Claims.

The invention relates to internal combustion engines of the type whereinfuel under pressure is injected into the engine cylinders, and has for ageneral object to supplement the usual regu- 5 lating system of theengine by providing a safety device which operates upon the occurrenceof abnormally high engine speed, to reduce the pressure on the fuel lineto a low value, thereby safeguarding the engine against injury in casethe ordinary fuel regulating system should fail to operate properly.

Diesel engines, for example, Aare in common use wherein fuel oil underpressure is supplied from a common manifold to the various cylindersthrough branch connections in which are located mechanically actuatedvalves which are controlled by a speed governor, to admit quantities offuel regulated according to the speed of the engine. And in applying thepresent invention 20 to Diesel engines, a safety device is employedwhich under abnormally high speed conditions automatically reduces thefuel pressure in the manifold to a low point, preventing furtheroverspeeding; however, a fairly low pressure is preferably maintained inthe manifold under such conditions, to prevent the fuel system frombecoming air bound. It should be understood that the principles vof theinvention are applicable to other internal combustion engines whereinliquid or gaseous fuels are supplied under pressure.

Further objects and advantages of the invention will be in part obviousand in part specifically referred to in the description hereinaftercontained which, taken in conjunction with the accompanying drawingsdiscloses a preferred embodiment of the invention. Such embodiment,however, is to be considered as merely illustrative of the principles ofthe invention. In the draw ings'- Fig. 1 is a view partly in section andmore or less diagrammatic of an overspeed device adapted to operate inaccordance with the invention.

Fig. 2 is a sectional view showingsuch device in relationto a typicalengine assembly'.

The invention is disclosed as applied to a Diesel engine of the typeabove referred to wherein oil is maintained under injection pressure ina manifold I8 from which branch pipes I6 lead to the various cylinders;suitable means is provided regulating the amounts of fuel supplied tothe cylinders under different operating conditions. In applying thepresent invention to an engine of the above type, anl overspeed deviceis employed having an overspeed valve connected to the manifold I8,which remains closed or inactive under into the fuel line.

1931, serial No. 556,471

normal operatingconditions, but which is actuated under abnormally highengine speeds, to relieve the pressure within the manifold I8.

As shown in Fig. 1, for example, this overspeed valve includes acasing36 in which operates a sliding valve 31 having a reduced portion 38which connects the ports 39 and 40 when valve 31 is raised. The port 38is connected by a pipe coupling 4I and pipe 42 to the fuel manifold I8.and the port 40 is connected by a, pipe 45 to the source of fuel, andhence when valve 31 I is raised as above described, the fuel pressure.in manifold I8 may be relieved. The port 40, however, is'normallyclosed by a relief valve 43 which also closes a port 44 communicatingwith the pipe 45 as above mentioned. A spring 46 may be adjusted bythethreaded plug 41 to control'the pressure at which therelief valveoperates. As shown, a cap 48 is threaded on. .the ex- ,.terior of theplug 41.

'Ihe position of the valve member 31 is controlled according 'to thespeed of the engine by any suitable type of speed governor, such asresponsive mechanism indicated diagrammatiycally at 60 in Fig. 1. Itwill be understood that this valve may be operated from the speedgovernor such as commonly employed in engines of the above type,although I prefer to employ a separate governor for this purpose, toinsure the relief of pressure on the fuel line in ease the usualgovernor should beout of order. l

'Ihe valve 31 is moved by the governor 60 in such manner as to connectthe ports 3!) and 4I) upon the occurrence of a predetermined abnormallyhigh engine speed and under these conditions the fuel pressure inmanifold I8 will be high enough to unseat the relief valve 43, thusrelieving the pressure in manifold I8 down to a point at which spring 46moves the valve 43 to closed position. In applying the invention toDiesel engines, the spring 46 is preferably set to return Valve 43 toclosed position at a fuel pressure somewhat above or at least equal toatmospheric pressure, to prevent air from getting In fact the pressuredrop in manifold I8 caused by the operation of the overspeed device,need not be so great as to stop the engine entirely, but merelysuilcient to prevent continued operation at unduly high speed.

In Fig. 2 the overspeed device above described is shown in relation to aDiesel engine assembly which should be regarded as merely typical and itWill be understood that the invention is not limited in its applicationto engines of this par- Cil which uid under pressureis supplied by apump I9, which draws fuel from a fuel supply tank 20 and delivers itunder pressure through a pipe 2l to the common manifold I8. The pump I8is operated from the crank shaft b y means of a sprocket chain 22 drivenby a sprocket wheel 23 connected to a gear wheel 24 meshing with a gearwheel 25 on the crank shaft I4. The

sprocket chain, as indicated passes over a sprocket wheel 26 which bysuitable drivingv connections, as indicated, operates the pump I9. Thesprocket chain'22 also passes over asprocket wheel 2l secured on the camshaft 28 which carries cams 2S operating on rollers on reciprocatingplungers 30 which operate bell cranks 3I connected to the needle 32 ofthe injection valve I5.

A wedge 33 controlled by the governor 3l and lying between the plunger30 and the bell crank 3| controls the amount of fuel injected. Theconstruction is such that as the load on the engine increases and itsspeed decreases, the wider portion of the wedge 33 is moved in betweenthe plunger and the bell crank to cause the valve to be lifted highervtoincrease the amount of fuel oil delivered at each injection, and as thespeed increases the wedge is withdrawn to reduce the amount of fuel oildelivered at each injection, thus limiting the speed of the engine whennot under load.

The governor 60 shown diagrammatically inl Fig. 1 may be regarded ascontained within the housing 35 of Fig. 2, and driven in any suitablemanner, as by sprocket 65 (Fig. 2) meshing with chain 22. The overspeedvalve casing 36 is shown mounted upon the housing 35', with the pipe I2connected to the pipe 4I which leads to the manifold I8, and the pipeconnected to the fuel supplyvtank 20.

As shown in Fig. 2 the valve casing 38 may also be provided .with apassageway 16 communicating with port M and leading to the space aroundthe bottom of valve. stem 31, so that any fuel which leaks past thevalves may be carried pipe 11 indicated at the botspirit of thisinvention, are comprehended withinv the terms of the appended claims.

I claim:

1. 'Ihe combination with an engine of the class described of a fuel lineadapted to supply fuel under pressure to the engine cylinders, speedcontrolled means for regulating the amounts of fuel so supplied, aseparate speed responsive mechanism, and means actuated by said speedresponsive mechanism under `abnormally high speed conditions forrelieving the pressure in said fuel line, said last mentioned meansincluding a valve acting to limit the degree of such pressure relief.

2. The combination with an engine of the class described, means fordelivering fuel under pressure to theengine cylinders, means forregulating the amounts of fuel so supplied, a relief valve adapted to beoperated by the fuel under pressure for reducing the pressure of thefuel, and means automatically operable as the engine attains apredetermined speed for establishing com- -rnunication between the fuelunder pressure and the relief valve to operate the relief valve.

3. The combination with an engine of the class described, of a fuel lineadapted to supply fuel under pressure to the engine cylinders, means forregulating the amounts of fuel so supplied, and means responsive tospeed conditions for relieving the pressure in said fuel line below thenormal pressure under abnormally high speed conditions and for'restoring normal pressure under normal speed conditions.

4. In combination with an engine of the class described, of a fuelmanifold connected to the engine cylinders to supply fuel thereto, meansfor supplying fuel under pressure to said manifold, means for regulatingthe amounts of fuel so supplied to the cylinders, a valveA connectedbetween said manifold and a point at lower pressure, and meansresponsive to speed conditions for opening and closing said valverespectively to relieve the pressure in said manifold under abnormallyhigh speed conditions and to restore normal pressurev under normal speedconditions.

i -CHARLES' M. BOVARD.

